package lj.leetcode.code96;

/**
 * @author 86187
 */
class Solution {
    public int numTrees(int n) {
        int[] dp = new int [n + 1];
        dp[0] = 1;
        for(int i = 1; i <= n; i ++){
            for(int j = 1; j <= i ; j++){
                dp[i] += dp[j - 1] * dp[i - j];
            }
        }
        return dp[n];
    }
}
